“We've talked about the Office of Legal Counsel memos on targeted killings, I've been asking for some time,” said Leahy to Holder at Wednesday’s oversight hearing of the Justice Department (DOJ).

“You and I have had discussions about this, and I realize the decision is not entirely in your hands, but it may be brought to a head with a subpoena from this office, from this committee,” Leahy said.

So far, the administration has only provided the OLC memos to the Intelligence committees, which it did ahead of a hearing to consider confirming John Brennan as director of the CIA.

A final Senate vote on Brennan's confirmation was being delayed Wednesday by senators who were also asking for more information about the drone program.

Holder told senators on Wednesday that he was sympathetic to the demands of the Judiciary panel, which oversees DOJ, and that he would try to make their case to other officials in charge of deciding whether to share the legal opinion.

“I have heard the committee express the desire to see these memoranda,
and I will — let me be careful here, but I will be bringing that to the
attention of the appropriate people within the administration," Holder said. "I am not
unsympathetic to what you are saying.”

The nation’s top cop also sought to cool speculation that the OLC justification opened the door for U.S. government and military officials to bypass court proceedings within the United States and order the killing U.S. citizens on American soil if they are suspected of carrying out terrorist activities.

“The government has no intention to carry out any drone strikes in the United States,” he said. “It's hard for me to imagine a situation in which that would occur.”

On Wednesday, Holder referred to the difficult decision former President George W. Bush and Vice President Dick Cheney had to make about whether to shoot down United Airlines Flight 93, which had been hijacked with more than three dozen U.S. citizens aboard and was believed to be targeting the U.S. Capitol.

It was "among the most difficult decisions that President Bush [and] Vice President Cheney had to make to give that order, but I think it was appropriate," said Holder. Passengers eventually overtook the terrorists on the flight, which crashed in Pennsylvania.

Concern over the OLC memos took center stage at Wednesday’s hearing, with members on both sides of the aisle questioning Holder about the details contained within the documents and the administration’s reluctance to show them to the committee.

Lee referenced a copy of a DOJ white paper that was leaked to NBC News last month that concludes that a lethal strike against a senior operational leader of al Qaeda — or an affiliated terrorist group — can occur if a three-part test is met. A high-ranking American intelligence official must have determined that the person poses an “imminent threat,” the person’s capture is not feasible and a strike on that person is conducted according to the laws of war governing use of force.

“The condition that an operational leader present an ‘imminent’ threat of violent attack against the United States does not require the United States to have clear evidence that a specific attack on U.S. persons and interests will take place in the immediate future,” the 16-page white paper states.

“What does imminence mean if it doesn’t have to involve something immediate?” Lee asked Holder at the hearing.

Holder said Lee hit upon a strong reason for why members of the committee should be shown the OLC opinions.

“I think that white paper becomes more clear if it can be read in conjunction with the underlying OLC advise,” said Holder in response. “It is one of the strongest reasons why the sharing of the opinions — the OLC advice — with this committee makes sense.”

In a speech at Northwestern University last March, Holder first laid out the administration’s justification for targeting U.S. citizens abroad, saying that the government’s definition of “imminent threat” consisted of three criteria: there was a limited open window for attacking the person, a grave possible harm that not attacking the target could have on U.S. civilians, and a strong likelihood that targeting the person would head off a future attack against the United States.

Concern over the government’s targeting of U.S. citizens abroad first came to a head in 2011, when it was revealed that U.S. officials targeted and killed American-born Anwar al-Awlaki in a drone strike. Al-Awlaki was widely known for inciting attacks against the United States, such as the 2009 Fort Hood mass shooting, the thwarted “underwear” bombing of a U.S.-bound plane and the failed Times Square bombing in 2010.